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IAS Prelims Exam: NCERT Physical Geography: THE ORIGIN AND EVOLUTION OF THE EARTH

Mar 1, 2016 14:21 IST

    Q.1. Consider the following statements

    1. Nebular hypothesis believed planets are formed out of cloud of material, mainly containing hydrogen and helium.
    2. Big bang theory was the first to provide evidence that planets are rotating round sun.

    Select the correct answer from the following codes

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: a

    Explanation:  Nebular hypothesis believed planets are formed out of cloud of material, mainly containing hydrogen and helium associated with youthful sun. Revised nebular hypothesis provided that sun was surrounded by solar nebular containing mostly hydrogen and helium along with dust, Big Bang Theory on origin of universe is most popular, It provided evidence that universe is expanding.

    Q.2. Consider the following statements

    1. A light year is a measure of time and distance.
    2. Nebula is huge cloud formed by the accumulation of hydrogen gas.

    Select the correct answer from the following codes

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: b

    Explanation: A light year is a measure of distance and not of time. The distance the light will travel in one year is taken to one light year. A galaxy starts to form by accumulation of hydrogen gas in form of very large cloud called Nebula.

    Q.3. Consider the following statements

    1. Jovian planets were formed few million years after terrestrial planets.
    2. Jovian planets are Jupiter like planets mostly of hydrogen and helium with high densities the terrestrial planets.

    Select the correct answer from the following codes

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: d

    Explanation:  All the planets were formed in same period sometime about 4.6 billion years ago. Jovian planets are larger than terrestrial planet and have thick atmosphere. Terrestrial planets are made of rocks and metals have relatively higher densities.

    Q.4. The thin atmosphere of planet earth initially had which of the following gases.

    1. Methane
    2. Hydrogen
    3. Helium
    4. Oxygen

    Select the correct answer from the following codes

    a. Only 1,2 and 3
    b. Only 2,3 and 4
    c. Only 2 and 3
    d. Only 2 and 4

    Answer: c

    Explanation: The planet earth initially was a barren, rocky and hot object with a thin atmosphere of hydrogen and helium.

    Q.5. Consider the following statements

    1. In primordial stage initially temperature of earth gradually increased.
    2. Density of material decreases from core to crust.

    Select the correct answer from the following codes

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: a

    Explanation: The earth from crust to core, density of material increase. The earth was mostly in a volatile state during its primordial stage. Due to gradual increase in density the temperature inside has increased. As a result the material inside started getting separated depending on their densities. This allowed heavier materials (like iron) to sink towards the centre of the earth and the lighter ones to move towards the surface.

    Q.6. The gases present in significant proportion in present atmosphere of earth is

    1. Hydrogen
    2. Nitrogen
    3. Carbon dioxide
    4. Oxygen

    Select the correct answer from the following codes

    a. Only 2 and 4
    b. Only 2,3 and 4
    c. Only 1 and 4
    d. Only 2 and 4

    Answer: d

    Explanation: The present composition of earth’s atmosphere is chiefly contributed by nitrogen and oxygen.

    Q.7. Consider the following statements

    1. Since primordial stage nitrogen is the chief component of earth’s atmosphere.
    2. Hydrogen and helium are among the gases which were outpoured from the interior of earth through degassing.

    Select the correct answer from the following codes

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: d

    Explanation:  The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. This happened not only in case of the earth, but also in all the terrestrial planets, which were supposed to have lost their primordial atmosphere through the impact of solar winds.

    Q.8. Consider the following statements

    1. After the evolution of atmosphere carbon dioxide in the atmosphere caused more rains.
    2. Significant amount of free oxygen in the atmosphere was initially contributed by terrestrial planets.

    Select the correct answer from the following codes

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer:c

    Explanation: As the earth cooled, the water vapour released started getting condensed. The carbon dioxide in the atmosphere got dissolved in rainwater and the temperature further decreased causing more condensation and more rains. Life was confined to the oceans for a long time. Oceans began to have the contribution of oxygen through the process of photosynthesis. Eventually, oceans were saturated with oxygen, and 2,000 million years ago, oxygen began to flood the atmosphere.

    Q.9. Which of the following is true about terrestrial planets?

    1. Earth being terrestrial planet have relatively high density than Jovian planets.
    2. The terrestrial planets are smaller and their lower gravity could not hold the escaping gases.

    Select the correct answer using following codes.

    a. Only 1
    b. Only 2
    c. Both 1 and 2
    d. Neither 1 nor 2

    Answer: c

    Explanation:
    Mercury, Venus, Earth and mars are called as the inner planets as they lie between the sun and the belt of asteroids the other five planets are called the outer planets. The first four are called Terrestrial, meaning earth-like as they are made up of rock and metals, and have relatively high densities. The rest five are called Jovian or Gas Giant planets. Jovian means Jupiter-like.

    Q.10. Which one of the following is not related to the formation or modification of the present atmosphere?

    a. Solar winds
    b. Degassing
    c. Differentiation
    d. Photosynthesis

    Answer: c

    Explanation:
    The composition of the atmosphere was modified by the living world through the process of photosynthesis. The early atmosphere, with hydrogen and helium, is supposed to have been stripped off as a result of the solar winds. The early atmosphere largely contained water vapour, nitrogen, carbon dioxide, methane, ammonia and very little of free oxygen. The process through which the gases were outpoured from the interior is called degassing.

     

    DISCLAIMER: JPL and its affiliates shall have no liability for any views, thoughts and comments expressed on this article.

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